In many ways, Aristotle's Poetics read like a set of lecture notes on the drama of his time. He is careful to define exactly what he means and supports his generalizations by referring to earlier and contemporary authors and artists. His analysis and description of poetry and tragedy in a number of ways are directed against the teachings of Plato, who dismissed poets from his Republic as encouraging faulty emotions in the audience. The discussion of tragedy in Aristotle's Poetics had a profound influence on critical attitudes to drama in the Renaissance. Classically educated writers like Sir Philip Sidney, or Shakespeare's contemporary dramatist, Ben Jonson, took Aristotle's descriptions of the drama of his time as prescriptions for tragedy as a whole. Most notably, they accepted what were thought of as the three "unities": time (the plot should deal with events occurring within a single day), place (the scene should take place in one location) and action (there should only be a single plot, with no unnecessary digressions). Shakespeare was probably aware of the concept of the unities; his early play The Comedy of Errors adheres to them, as does one of his final works, The Tempest; his other plays conform more closely to the conventions evolved on the early English stage, where plots were more flexible.

2The Poetics did introduce a number of valuable critical concepts, of more lasting value than the "unities":

hamartia, here translated effectively as "error or frailty"; it can also be thought of as a shortcoming, or as an excess of some characteristic. Aristotle sees the tragic protagonist's fall as the result of hamartia. Earlier Victorian translations of the Poetics described hamartia rather moralistically and reductively as a "fatal flaw"—and this definition will still be found widely on the Internet. Seen as an error or excess, hamartia is a powerful way of understanding some Shakespearean tragic figures: Hamlet's desire to think carefully about his actions rather than rashly charging ahead with revenge can be seen as an error, and perhaps as excessively analytical, but it is hard to see it as a flaw. Lear's desire at an advaced age to "shake all cares and business from [his] age" (TLN 44) is a clear indication of frailty, and of a lack of self-awareness, but again the concept of a single or simple flaw is reductive.

catharsis, here translaged as "purgation," is also sometimes translated as "purification." In response to Plato's atack on poetry, Aristotle is seeking a justification for tragedy; he claims that its emphasis on death, violence, and powerful emotions is a kind of uplifting moral medicine.

anagnorisis ("recognition") is not limited to tragedy—many concluding scenes in comedy and romance involve the sudden recognition of who characters really are. In Othello, the revelation of Iago's true nature is a textbook example; in King Lear Edgar reveals his multiple disguises in the final scene. Anagnorisis can also be extended to a more metaphorical level as a description of the moment of self-revelation some characters experience: Lear's realization of the routine suffering of his subjects as he is himself subjected to the violence of the storm ("I have ta'en / Too little care of this [TLN 1814]), and Gloucester's moving insight, "I stumbled when I saw" (TLN 2200).

peripeteia, "reversal of the situation," as Aristotle comments, is often the result of recognition. Some new knowledge or event radically changes the characters' understanding of reality; again, Edgar's revelation of his disguise causes a reversal of Edmund's status. More striking is the reversal of Albany's expectations as King Lear enters with the dead Cordelia in his arms.

pathos, in Aristotle's use of the word, refers to "suffering." Pity (eleos) is invoked in the audience by watching "the scene of suffering" (see part IX).

mimesis, translated as "imitation," comes close to what modern audiences would see as realism—the kinds of responses from characters that we would recognise as "actions in real life."